A novel approach in assessing the antimicrobial efficacy of eye drop products
Posted: 4 May 2016 | | 1 comment
The microbial contamination of medicinal products constitutes a continuous threat to the health of consumers, which may negatively impact pharmaceutical companies’ reputability. However, multidose sterile pharmaceutical products are prone to contamination either from the normal flora of the human body or from the surrounding environment, following their misuse by patients. With the absence of strict medical supervision from medical professionals, patients can infect themselves with such a contaminated product. The study described in this article provides a new prospective view on the preservative efficacy test (PET) to assess the potency of antimicrobial agent(s) in two formulae of eye drops as well as quantitatively determining the risk of recontamination by the consumer.
Several studies have documented contamination of preserved eye drops, the rate of which varies between 2.2% and 34.8%1,2. Contamination of these products can lead to serious eye infections, especially when the ocular surface defenses are compromised. Application of contaminated eye drops may lead to potentially devastating consequences in patients, such as the development of ocular surface diseases or wound leaks following intraocular surgery3. Previous studies on preserved eye drops have found high contamination rates in β-blockers, steroid drops and ocular lubricants4. A previous study has shown that contamination occurs in both inpatient and outpatient settings, while eye drops used by outpatients are more likely to be contaminated than those used by inpatients. The highest rates of contamination were seen in non-antibiotic bottles used in such outpatient settings (38%)3.
Previous studies on preserved eye drops have concluded that pathogenic Gram-negative bacteria are more likely to grow in the bottle reservoir than Gram-positive organisms, which are mainly commensal in the environment4,5. Poor technique in administering the drops is a further risk factor for contamination, especially if patients self-administer in an outpatient setting. Elderly patients, who may have poor vision and coordination, can inadvertently touch their eyes or skin with the pipette dropper and, on insertion of the dropper back into the container after use, may also contaminate the container. Patients who must use these drops very frequently greatly increase the risk that any or all of the above situations may occur3. Clinical trials of the designs of eye drop containers – all of which are plastic, squeezable and have screw-on caps – have not been carried out to determine their effectiveness at reducing contamination. However, the design can result in microbial keratitis6,4.